His are accessories illegal?
Nothing on that pistol is illegal. Have all the letters from the atf to back it up.
Don't buy a dam bushmaster pistol, too many proprietary parts. Don't buy anything premade unless you get a smoking deal. Build it. Buy the lower, have it marked on the 4473 as a pistol or other and get to work. I'd advise you to do a 10.5" or longer upper. You'll want a carbine length gas system, way less problematic.